Bushing



April 17, 1934.

F. E. AURAND 1,955,165 4 BUSHING Filed Decrr 23, 1932 2 Sheets-Sheet l April 17, 1934. F. E. AURAND BUSHING Filed Deo. 25. 1932 2 Sheets-Sheet 2 jfl 2*/@72 f' Fw? MT @www ffy Wm M Patented pr. 1.7i, 1.934

UNITED STATES PATENT OFFICE Claims.

This invention relates to bushings, and is more particularly directed to bushings adapted for use in transformers, circuit breakers, and other types of electrical equipment in which conductors and cables are passed through the walls of the device for connection to terminals disposed therein, and in which a fluid-tight seal must be provided through the walls.

Bushings of this type are generally adapted to have abutting engagement with the outer surface of the walls through which they extend, and are provided with various means for drawing the bushing member proper tightly up against this surface. These tightening means, however, are u relatively large in size, usually comprising a plate member having an opening receiving the inner extending end of the insulating member. This plate member ordinarily engages under a coiled spring encircling the insulating member and fitting into a groove formed in the surface thereof, or engaging under any other suitable abutting means, and is provided with screws bearing upon the inner surface of the wall of the device for raising the plate therefrom, thus drawing the insulating member inwardly and forcing the abutting portion of the bushing tightly against the outer wall.

However, due to the concentrated application of pressure upon the wall immediately under the screws, there is a tendency for the wall to buckle between these points, thus breaking the fluidtight seal and allowing the escape of oil, admission of dust to the interior of the housing, and other undesirable effects. Further, in order to secure adequate bearing surface for bushings of this type, the plate member must be of such size that its use is limited to only such situations as will provide ample room to allow placing the plate over the bushing and providing for access to the 4o screws for tightening them to draw the bushing member into fluid-tight engagement with the wall.

It also is the usual practice, in the use of some types of bushings, to apply an insulating coating of tar, asphaltum, litharge, or the like, over the entire inner portion of the bushing in order to provide an effective seal. Thus, when the bushing has to be removed, or repairs are to be made, it is necessary to use considerable effort to chip out this coating of insulating compound, and this chipping weakens the walls of the device resulting in misaligninent thereof, and often in breaking of the insulating member.

Other types of bushings of which I am aware depended upon the threaded engagement of a collar upon the inner extending end of the bushing member to draw it into proper position to provide a fluid-tight seal through the wall. However, any rotational movement of the bushing member or of the collar, after assembly, results in loosening of the seal and consequently leakage through the wall.

I therefore propose to provide a bushing which has parallel surfaces engaging the inner and outer surfaces of the wall about the periphery of the opening through which the bushing extends. This parallel surface engagement prevents any buckling of the wall since the pressure is equally distributed about the entire periphery of the opening.

In the preferred embodiment of the invention, the bushing comprises a substantially cylindrical insulating member having a central opening for receiving the conductor, which member is provided with a shoulder portion adapted to engage the outer defining surface of the opening in thewall of the transformer, or other device through which the bushing passes. A suitable gasket may be interposed between the shoulder and the outer surface of the wall to provide sealing means therebetween, if desired. An annular ring, of substantial depth to impart to it the necessary rigidity, is disposed over the inwardly extending portion of the bushing member, and seats upon the inner surface of the wall.

The insulating bushing member is provided with an annular outer groove forming a second shoulder disposed above and facing the first shoulder, which shoulder is engaged by a plurality of ring segments having screw members seating in corresponding recesses formed in the ring member. By turning the screw members downwardly, the segments are raised from the ring, and thus engage against this second shoulder to draw the insulating member upwardly into Atight abutting engagement with the outer surface of the wall, the ring at the same time lbeing forced downwardly into engagement with the inner surface of the wall, forming a seal comprising the parallel surfaces of the abutting portion of the insulating member and the ring disposed on opposite sides of the supporting wall.

By the provision of the ring segments, the bushing can be installed in walls where only a limited space is available, since the segments can be slipped in under the groove and engaged in the annular ring, and the ring with the segments carried thereby can then be rotated about the inner extending end of the bushing member to place the segment in a position which otherwise would be inaccessible. Further, it is unnecessary, in the present invention, to employ insulating compound or the like to provide sealing means over the inner surface ofthe bushing member since, by the provision of the parallel abutting surfaces adjacent the opening through which the member extends, the seal can be made sufciently effective to prevent leakage of oil therethrough, and is maintained in this condition by the engagement or" the ring segment with the shoulder on the inner extending end of the bushing member. Thus the necessity of chipping out insulating compound, which weakens the joints of the wall, thus providing leakage therethrough, and which also usually results in breaking of the insulating member, is avoided.

Also, the segments, if desired, can be so formed as to counteract and take up any expansion or contraction of the bushing construction due to temperature or moisture variations.

The following detailed description of a preferred embodiment of the invention, taken in connection with the accompanying drawings, will disclose to those skilled in the art the construction and operation of my invention, as well as the manner in which the invention may be assembled into position.

'In the drawings:

-Figure v1 is a plan view of a transformer housing, with the cover removed, showing one manner in which the invention may be employed;

Figure-'2 is-a side elevation, with a part of the housing ybroken away, of the transformer of Figure 1;

Figure 3 is a top plan View of the bushing installed in position upon a supporting wall;

Figure -4 is a side elevation, partly in section, of `lthefbushing shown in Figure 3;

Fig-ure 5 is a perspective View of the ring memberproviding for abutting engagement upon the inner surface of the wall, with a portion broken away to show the extent of the recesses formed -inthemembem `Figure 6 is aperspective view of the ring segment usedl for drawing the insulating member into tight abutting engagement with the wall;

Figure Y7 is a perspective view of a modified `form of a ring segment; and

Figures 8A, 8B and 8C disclose the various steps for installing a bushing of the present invention in -a position in which only a limited space is available for assembling the various parts thereof.

=Referring now in detail to the drawings, the transformer housing 10, shown in Figuresl and vl2, is -.provided with the ordinary supporting `bracket members 11, and is provided with a laterally oiTset` portion 12 which has the: conductors -l-SeXtending therethrough. |Ihe housing 10 is Ialso. provided with the oset ear portions 114 and 15, having theconductors 16 extendingtherethrough. Bushings, indicated generally at 17, provide-av fluid-tight seal through which the concductorsrl-S and 16 extend into the interior of the `housingy 10. vIt-is to be understood that the bush- ,ing-may bev employed in connection with other types of equipment, and is shown in connection if-'withfa'V transformer housing only for purposes of illustration.

:Referring now in detail to Figures 3 to 7, inclusive, ythe bushing 17 comprises the substanfftially cylindrical insulating member 20 having the A-shoulderzl formed thereon. This shoulder-is ffadapted to have abutting engagement against the -wlall--l2of'the transformer housing, ora similar rthreaded openings supporting member. Interposed between the shoulder 21 and the surface of the wall 20, I preferably provide a gasket member 22 which may be formed of cork, sheet asbestos, or the like. The gasket serves to provide additional means for sealing the opening against leakage of oil, or the like. Extending centrally through the member 20 is the conductor opening 24, which provides for admission of the conductor leading to the interior of the casing. An interior annular groove 25 is provided for forming keying means to seal the conductor within the bushing. When the conductor has been placed in position, suitable insulating compound is poured into the interior of the bushing, and engages in the groove 25 for keying the conductor in position.

Disposed about the outer periphery of the inner extending end of the member 20 is an annular ring 27, shown more in detail in Figure 5. This ring 27 is of suiicient depth to impart to it the necessary rigidity for providing an abutting surface on the inner surface of the wall 12 so that the parallel engaging surfaces of the ring and-,the abutting shoulder 2l of the member 20 kwillfprovide a continuous seal about the periphery of the opening 28 formed in the wall.

The ring member 27 is provided with a plurality of recesses 29 which provide seating lengagement for a plurality of screw members 30 carried in threaded openings formed in the ring segment 31 shown in Figures 6 and ,7. These screw members 30 are preferably threaded only at their upper portion, the lower end comprsllgza stud vportion having seating engagement in the recesses 29.

The ring segments 31 are provided with an upper inwardly beveled edge which is adapted to have abutting engagement with a shoulder 33 formed in the insulating member 20. The shoulder 33 is formed by means of an annular groove 34 formed in the periphery of the member v20 immediately above the wall l2. Upon threading the screw -members 30 downwardly, the ring segments 3l are raised, since the lower ends of the screwmembers 30 seat in the recesses 29 formed in the ring, 27, and the raising of the segments 3l draws the member 20 upwardly into tight labutting engagement with the supporting wall, the inner edges of the ring segments abutting against the shoulder 33 formed in thefmember20. It will be noted that there is substantially continuous peripheral engagement of the elements 31 with the shoulder 33 so that the member 20 will be uniformly-lifted and so that equal pressure lcan be applied at all points about the periphery of the abutting shoulder 21.

If desired, the ring lsegments may-comprise semi-circular members, as shown, ormay be-composed of a greater number of segments, depending upon the particular type of installation desired, and the space Vavailable for the installation.

Considering in `detail Figure 7, the segment disclosed therein is so formed as to counteract the effects of expansion and contraction ,of the ring 27, the screw members 30, and the segments 3l, due to temperature or moisture variations, and isprovided with raised portions intermediatetlie 41 receiving screw members, such as the members-30. The curvature'of this member provides a resiliency that will accommodate the expansion and contraction-ofv thev related parts of the assembly, and thus will minimize thedanger of breaking ofthe insulating member 20due toexpansion or contraction.

Considering now in detail Figures 8A, 8B and 8C which show the particular method of assembling the insulator in position in a situation in which only a limited space is available for receiving the bushing, I have disclosed a housing construction, formed by the vertically extending wall 45, in which an insulating bushing is adapted to be positioned, and wherein access to only one side of the bushing is available, due to the limited space. In such an installation, the bushing member 20 is inserted into the position shown in Figure 4, the ring member 27 is slipped over the inwardly extending end of the bushing, and a ring segment 31 is passed under the abutting shoulder 33 of the member 20, and the screws 30 are turned downwardly sufficiently to seat the screw members in the recesses 29 to hold the segment in position. The entire ring member, together with the segment, is then rotated in the direction indicated by the arrow in Figure 8A, to the position shown in Figure 8B.

In this position, the segment 31 has now been disposed in a position which otherwise could not be attained by the usual method of installation. In this position, it is relatively easy to thread the members 30 downwardly sufficiently to draw the insulating member 20 upwardly into abutting engagement. After the bushing assembly has been disposed in the position shown in Figure 8B, the second ring segment is placed in position as shown in Figure 8C.

The threaded members 30 are then screwed down uniformly to draw the member 20 into tight abutting engagement with the lower edge of the supporting wall 12', and the ring member 27 is forced downwardly into tight abutting engagement with the inner surface of the wall 12. In this manner, an effective seal is provided about the opening 28 in the wall member, and uniform application of sealing pressure about the entire periphery of the opening is obtained.

It will be noted that the screw members 30 are so disposed about the periphery of the ring segment 31 that the line of lifting force exerted thereby will fall along the inner edge of the shoulder 33, and thus cooking of the insulator member will be prevented. This spacing may be varied, within limits, to accommodate any number of ring segments, without eliminating this feature. Also, by this spacing, the lateral component of force exerted by the members 30 with respect to the recesses 29 will be minimized, and misalignment of the screw members with respect to the recesses will be prevented.

Further, it will be apparent by the provision of the relatively deep rigid ring member 27, a substantial and rigid'abutting surface is provided upon the inner surface of the wall 12, which surface is disposed directly above and parallel to the abutting surface formed by the shoulder 2l and gasket member 22. This produces an effective seal, which can be maintained under any desired compression by means of the threaded screw members 30.

It is to be understood that various modifications and changes may be made with respect to the invention disclosed, without departing from the limits thereof, and I do not intend to be limited to the exact details shown and described, but only as defined by the scope and sphere of the appended claims.

I claim:

l. A bushing comprising an insulating member having opposed annular shoulders, rigid sealing means disposed about said member between said shoulders, a plurality of ring segments abutting against one of said shoulders, and means carried by said segments and seating in recesses formed in the sealing means for aligning said segments above said sealing means, said means comprising screw members for forcing said segments away from said sealing means to draw said other shoulder toward said sealing means.

2. In combination, a supporting planar member having an opening therein, an insulating member extending through said opening and having an annular shoulder engaging said supporting member about said opening, a ring disposed about the extending portion of said insulating member and bearing against the opposite side of said supporting member in aligned position with said shoulder, an annular groove in the outer surface of said insulating member, ring segments engaging in said groove, and means supporting said segments and seating in said ring for drawing said insulating member into sealing engagement with said supporting member.

3. In a housing having a planar surface provided with an opening, a sleeve member extending through said opening, an angularly extending surface defining a space only slightly larger than the external diameter of said sleeve member about a substantial portion of the periphery of said member, said sleeve member having an annular shoulder, a ring adapted to fit down over the sleeve member, a plurality of segmental bearing members engaging under said shoulder, and means carried by said segmental members and seating in said ring for raising said segmental members away from said ring to thereby raise said sleeve member.

4. A bushing comprising a cylindrical member having opposed annular shoulders, a rigid ring member disposed about said bushing between said shoulders, a sectional ring member abutting against one of said shoulders, and means carried by said sectional ring member and seating in said rigid ring member for holding said sectional ring member in abutting position with respect to said shoulders and for drawing said other shoulder toward said rigid ring member.

5. The combination with a bushing having sealing means disposed thereabout and having an annular shoulder disposed above said sealing means, of segments engaging about the periphery of said bushing beneath said shoulder, and means carried by said segments and seating in recesses formed in said sealing means for raising said bushing with respect to said sealing means, said segments being maintained in position beneath said shoulder and restrained against outward movement by the engagement of said raising 1 means in said sealing means.

FRANK E. AURAND. 

